The teacher has to provide many opportunities for students to demonstrate understanding at a higher level. Memorization of proper note names and syllables is not the same thing as knowing the rhythms deeply. Students should be able to manipulate tempo, perform alone and with others using identical and complementary rhythms, and practice silently (in their head). In addition, to saying the counting (or syllables), students should write rhythms within specified guidelines (time signatures, balance of notes and rests, including certain rhythm combinations, etc.) and perform them with fluency and accuracy.
What I am discovering is that even though it seems to take away from learning time, several assessments given in a variety of ways will provide students with more diverse practice opportunities. In addition, teachers will gain a better understanding of each of their individual student's strengths and weaknesses.